1. Field of Art
The present invention relates to a casting apparatus for casting a molten metal in a mold efficiently and safely in an inert or reducing gas atmosphere.
2. Prior Art
In casting an inflammable light alloy, such as a magnesium alloy, the molten alloy is cast in an inert or reducing gas atmosphere to prevent oxidation of the molten alloy. Examples of the inert or reducing gas used in the prior art processes are sulfur hexafluoride (SF.sub.6), carbon monoxide (CO) and sulfurous acid gas (SO.sub.2). However, in the conventional processes, a sintered mold is put in a chamber having an opened top and then one of the aforementioned inert or reducing gases is allowed to flow into the chamber to purge air with the flowing inert or reducing gas while making use of the fact that such an inert or reducing gas heavier than air. This purging operation in the conventional processes must be carried out gently and slowly to reduce the operation efficiency. In addition, there is a safety problem, since these gases are toxic to human being.